New here , with limited knowledge on the subject , so please forgive any obvious flaws:

What would you recommend as finish for a gun that just has been engraved, after having the original finish ( blue) removed ?
The gun is a Perazzi, black action, and now has some scroll&florals engraved.
I've seen some factory delivered guns , who had some kind of varnish(?) but it cracked over the years , and it didn't look very nice, although it did protect the gun until it cracked.
Thank you
HM

I suppose it depends what you really want. As it was blued originally a re-blue would work whether hot dip or rust blued. When the original blue was removed was the metal fairly smooth or did it have a lot of very fine pits (indicating the original finish was rust blued)? I would guess hot dipped for a production gun. When re-blued the engraving will show well enough though it will be subtle. If there is any gold or silver inlay it will certainly stand out through the blue. Be aware rust bluing can cause some minor damage to inlays more or less depending on the experience of the person who does the work.

To make the engraving stand out, after bluing the blue can be selectively removed from the engraving by painting fingernail polish or a stop off varnish where you want to keep the blue and remove it from the engraving with a rust remover like Naval Jelly. Inking the engraving after removing the blue will darken the cuts and enhance the engraving.

A somewhat more complex finish would be to electroless nickel plate the receiver and then ink the engraving, giving the whole thing the "French gray" look.

A varnish coat is normally used on a case colored item to protect the colors which will otherwise wear off easily.